• Journal of Applied Biological Chemistry
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• v.48 no.3
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• pp.113-119
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• 2005

O-methylation mediated by O-methyltransferases (OMTs) is a common modification in natural product biosynthesis and contributes to diversity of secondary metabolites. OMTs use phenylpropanoids, flavonoids, other phenolics and alkaloids as substrates, and share common domains for S-adenosyl-L-methionine (AdoMet) and substrate binding. We searched Arabiposis genome and found 17 OMTs genes (AtOMTs). AdoMet- and substrate-binding sites were predicted. AdoMet binding domain of AtOMTs is highly conserved, while substrate-binding domain is diverse, indicating use of different substrates. In addition, expressions of six AtOMT genes in response to UV and in different tissues were investigated using real-time quantitative reverse transcriptase-polymerase chain reaction. All the AtOMTs investigated were expressed under normal growth condition and most, except AtOMT10, were induced after UV illumination. AtOMT1 and AtOMT8 were expressed in all the tissues, whereas AtOMT10 showed flower-specific expression. Analysis of these AtOMT gene expressions could provide some clues on AtOMT involvement in the cellular processes.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.11a
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• pp.419-420
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• 2008

In this work, we report several experimental data capable of evaluating the phase transition characteristics of (InTe)x(GeTe)y (x = 0.1, 0.3, y =1) pseudo-binary thin films. (InTe)x(GeTe)y phase change thin films have been prepared by thermal evaporator. The crystallization characteristics of amorphous (InTe)x(GeTe)y thin films were investigated by using nano-pulse scanner with 658 nm laser diode (power : 1~17 mW, pulse duration : 10~460 ns) and XRD measurement. It was found that the crystalline speed of In-Ge-Te thin films are faster than $Ge_2Sb_2Te_5$[1] and also the crystalline temperature is higher. Changes in the optical transmittance of as-deposited and annealed films were measured using a UV-VIS-IR spectrophotometer and four-point probe was used to measure the sheeresistance of InGeTe films annealed at different temperature.

• Proceedings of the KSME Conference
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• 2003.04a
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• pp.1881-1884
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• 2003

In this experiment, the oxidations of p-Xylene (140-180 ppmv), one of the air pollutants as a VOC, using $UV/TiO_2$ photocatalyst is studied. In order to increase the specific surface area, the filter is coated by nano $TiO_2$ particles. The photodegradation system consists of a VOCs generator, a photocatalyst filter and a measuring equipment. Illumination is generally provided by two of 20 W black light lamps with 380 nm of wavelength. The filter coated by nano $TiO_2$ particles has a passing efficiency over 80% but a pressure drop of 9.0 $mmH_2O$ at 0.45 cm/s. The filter endurance is better than activated carbon at the same pressure drop.

• Rapid Communication in Photoscience
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• v.2 no.2
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• pp.64-66
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• 2013

Photoreduction of $CO_2$ into hydrocarbon fuels on the surface of photocatalyst is one of the breakthroughs in the field of photocatalysis. At present various approaches have been investigated with the aim of increasing the $CO_2$ conversion efficiency. The reactor for photoconversion of $CO_2$ plays a vital role in experimental setup. In this work an attempt was made to testify a newly designed the photoreactor for conversion of $CO_2$ into useful products. The photoreactor was specifically designed for simple operation bearing features of temperature and pressure control. The reactor has been tested successively with the standard titania, Degussa P25 yielding methane with moderate production rate of 30.8 $ppm{\cdot}g^{-1}{\cdot}h^{-1}$ under UV lamp with 365 nm wavelength. The methane yield obtained is comparable to the values reported in literature. Thus we anticipate that this experimental setup equipped with newly designed photoreactor can yield competitive amounts of fuels from $CO_2$ photoredcution via 365 nm UV light illumination on various photocatalysts.

• Journal of the Korean Chemical Society
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• v.43 no.1
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• pp.1-7
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• 1999

Metal colloidal particles have been prepared by a photo-chemical process in an aqueous solution containing semiconductor nanocrystallites. Metal colloidal particles produced in CdS and AgBr exhibit different absorption spectra. Au particles produced in solution with CdS show typical Au plasmon resonance absorption spectra. On the other hand Ag particles in solution with AgBr shows surface plasmon resonance absorption spectra which are red-shifted, as compared to that of a dispersion of homogeneous Ag colloidal particles in the same host. The extent of red-shift depends on the UV illumination time. This phenomenon is interpreted within the context of effective medium theory for small volume fractions. From the theory, a metal coated particle predicts Ag plasmon resonance, red shifted with respect to 400 nm that would be associated with a silver particle in solution. The absorption peak position is very sensitive to the coating thickness.

• Carbon letters
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• v.9 no.4
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• pp.294-297
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• 2008

A CNT-$TiO_2$ nano composite was prepared from titanium chloride ($TiCl_4$) via sol-gel process using multi walled carbon nano tube (MWCNT) followed by calcination at $450^{\circ}C$. Spectral analysis revealed that the formed $TiO_2$ resided on the carbon in anatase form. The effect of adsorption was investigated using aqueous solution of methylene blue and procion blue dye. The photochemical reaction of CNT-$TiO_2$ composite in aqueous suspensions was studied under UV illumination in batch process. The reaction was investigated by monitoring the discoloration of the dyes employing UV-Visible spectro-photometeric technique as a function of irradiation time. The catalyst composites were found to be efficient for the photodegradation of the dye.

• Journal of Ginseng Research
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• v.32 no.2
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• pp.114-119
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• 2008

Terpene synthase plays a key role in biosynthesis of triterpene saponins (ginsenosides) and is intermediate in the biosynthesis of a number of secondary metabolites. A terpene synthase (PgTPS) cDNA was isolated and characterized from the root of Panax ginseng c.A. Meyer. The deduced amino acid sequence of PgTPS showed a similarity with A. deliciosa (AAX16121) 61%, V. vinifera (AAS66357) 61%, L. hirsutum (AAG41891) 55%, M. truncatula (AAV36464) 52%. And the segment of a terpene synthase gene was amplified by reverse transcriptase-polymerase chain reaction (RTPCR). We studied expression of terpene synthase under stressful conditions like chilling, salt, UV, and heavy metal stress treatment. Expression of PgTPS was increased gradually after exposure to stresses such as chilling, salt, and UV illumination. But its transcription seems to be reduced by cadmium and copper treatment.

• Bulletin of the Korean Chemical Society
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• v.26 no.10
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• pp.1515-1519
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• 2005

Tungsten oxide-modified TiO2 thin films were formed on a glass substrate by sol-gel and dip coating processes using acetyl acetone as a chelating agent. The hydrophilic properties of the thin films were investigated with illumination of UV light. The dependence of water contact angle on material composition and morphology of the film is established with SEM image and AFM profile. The surface morphology was controlled with the change of precursor concentration. 0.01 M of tungsten oxide-modified Ti$O_2$ have shown the highest hydrophilicity after UV-irradiation. The effect of composition on photoinduced hydrophilicity of the W$O_3$-Ti$O_2$ films was also investigated. The films were characterized by XRD, SEM, AFM and XPS.

• Advances in nano research
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• v.7 no.1
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• pp.13-24
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• 2019

Well-crystalline $SnO_2$ nanoparticles of 4-5 nm size with different In contents were synthesized by hydrothermal process at relatively low temperature and characterized by transmission electron microscopy (TEM), microRaman spectroscopy and photoluminescence (PL) spectroscopy. Indium incorporation in $SnO_2$ lattice is seen to cause a lattice expansion, increasing the average size of the nanoparticles. The fundamental phonon vibration modes of $SnO_2$ lattice suffer a broadening, and surface modes associated to particle size shift gradually with the increase of In content. Incorporation of In drastically enhances the PL emission of $SnO_2$ nanoparticles associated to deep electronic defect levels. Although In incorporation reduces the band gap energy of $SnO_2$ crystallites only marginally, it affects drastically their dye degradation behaviors under UV illumination. While the UV degradation of methylene blue (MB) by undoped $SnO_2$ nanoparticles occurs through the production of intermediate byproducts such as azure A, azure B, and azure C, direct mineralization of MB takes place for In-doped $SnO_2$ nanoparticles.

• Polymer(Korea)
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• v.36 no.6
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• pp.795-802
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• 2012

Surface modification of a hydrophobic acrylic polymer film has been performed through simple chemical treatment to give a reactive surface. 2-Triphenylstannylthioethyl acrylate was polymerized under UV-illumination with various contents of a comonomer. When the polymer film was treated with fluoride ion, thiol functional group (SH) was generated on the film surface, which was observed through infrared absorption spectroscopy. The surface was functionalized by thiol addition reaction to acrylic chromophores. The SH content on the surface was controlled with a comonomer, tris(hydroxymethyl)ethane triacrylate, and examined with UV-Vis absorbance of the chromophore attached film. Similarly, a polymer film from 2-tributylstannylthioethyl acrylate was prepared. Destannylation from the triphenylstannyl and tributylstannyl surface completed after 30 and 5 min, respectively. The SH-exposed surface was modified with an isocyanate attached chromophore within 10 min, while acrylic chromophore required 24 h.